package com.dg11185.nearshop.view;

import com.android.nearshop.R;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Switch;

/**
 * android4.0以上的{@link Switch} 效果
 */
public class SwitchButton extends View implements android.view.View.OnClickListener {

    private Bitmap mSwitchBottom, mSwitchThumb, mSwitchFrame, mSwitchMask;

    private float mCurrentX = 0;

    private boolean mSwitchOn = true;// 开关默认是开着的

    private int mMoveLength;// 最大移动距离

    private float mLastX = 0;// 第一次按下的有效区域

    private Rect mDest = null;// 绘制的目标区域大小

    private Rect mSrc = null;// 截取源图片的大小

    private int mDeltX = 0;// 移动的偏移量

    private Paint mPaint = null;

    private OnSwitchButtonChangeListener mListener = null;

    private boolean mFlag = false;

    public SwitchButton(Context context) {
        this(context, null);
    }

    public SwitchButton(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public SwitchButton(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }

    /**
     * 初始化相关资源
     */
    public void init() {
        mSwitchBottom = BitmapFactory.decodeResource(getResources(), R.drawable.switch_bottom);
        mSwitchThumb = BitmapFactory.decodeResource(getResources(), R.drawable.switch_btn_pressed);
        mSwitchFrame = BitmapFactory.decodeResource(getResources(), R.drawable.switch_frame);
        mSwitchMask = BitmapFactory.decodeResource(getResources(), R.drawable.switch_mask);
        setOnClickListener(this);
        setOnTouchListener(new OnTouchListener() {

            @Override
            public boolean onTouch(View v, MotionEvent event) {
                return false;
            }
        });

        mMoveLength = mSwitchBottom.getWidth() - mSwitchFrame.getWidth();
        mDest = new Rect(0, 0, mSwitchFrame.getWidth(), mSwitchFrame.getHeight());
        mSrc = new Rect();
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setAlpha(255);
        mPaint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        setMeasuredDimension(mSwitchFrame.getWidth(), mSwitchFrame.getHeight());
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (mDeltX > 0 || mDeltX == 0 && mSwitchOn) {
            if (mSrc != null) {
                mSrc.set(mMoveLength - mDeltX, 0, mSwitchBottom.getWidth() - mDeltX, mSwitchFrame.getHeight());
            }
        } else if (mDeltX < 0 || mDeltX == 0 && !mSwitchOn) {
            if (mSrc != null) {
                mSrc.set(-mDeltX, 0, mSwitchFrame.getWidth() - mDeltX, mSwitchFrame.getHeight());
            }
        }// 这儿是离屏缓冲，自己感觉类似双缓冲机制吧
        int count = canvas
                .saveLayer(new RectF(mDest), null, Canvas.MATRIX_SAVE_FLAG | Canvas.CLIP_SAVE_FLAG
                        | Canvas.HAS_ALPHA_LAYER_SAVE_FLAG | Canvas.FULL_COLOR_LAYER_SAVE_FLAG
                        | Canvas.CLIP_TO_LAYER_SAVE_FLAG);

        canvas.drawBitmap(mSwitchBottom, mSrc, mDest, null);
        canvas.drawBitmap(mSwitchThumb, mSrc, mDest, null);
        canvas.drawBitmap(mSwitchFrame, 0, 0, null);
        canvas.drawBitmap(mSwitchMask, 0, 0, mPaint);
        canvas.restoreToCount(count);
        invalidate();
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            mLastX = event.getX();
            break;
        case MotionEvent.ACTION_MOVE:
            mCurrentX = event.getX();
            mDeltX = (int) (mCurrentX - mLastX);
            // 如果开关开着向左滑动，或者开关关着向右滑动（这时候是不需要处理的）
            if ((mSwitchOn && mDeltX < 0) || (!mSwitchOn && mDeltX > 0)) {
                mFlag = true;
                mDeltX = 0;
            }

            if (Math.abs(mDeltX) > mMoveLength) {
                mDeltX = mDeltX > 0 ? mMoveLength : -mMoveLength;
            }
            invalidate();
            return true;
            // 由该控件滑动到其它控件是会调用ACTION_CANCEL，但不会调用ACTION_UP
        case MotionEvent.ACTION_UP:
        case MotionEvent.ACTION_CANCEL:
            if (Math.abs(mDeltX) > 0 && Math.abs(mDeltX) < mMoveLength / 2) {
                mDeltX = 0;
                invalidate();
                return true;
            } else if (Math.abs(mDeltX) > mMoveLength / 2 && Math.abs(mDeltX) <= mMoveLength) {
                mDeltX = mDeltX > 0 ? mMoveLength : -mMoveLength;
                mSwitchOn = !mSwitchOn;
                if (mListener != null) {
                    mListener.onChange(this, mSwitchOn);
                }
                invalidate();
                mDeltX = 0;
                return true;
            } else if (mDeltX == 0 && mFlag) {
                // 这时候得到的是不需要进行处理的，因为已经move过了
                mDeltX = 0;
                mFlag = false;
                return true;
            }
            return super.onTouchEvent(event);
        default:
            break;
        }
        invalidate();
        return super.onTouchEvent(event);
    }

    public void setListener(OnSwitchButtonChangeListener listener) {
        mListener = listener;
    }

    public interface OnSwitchButtonChangeListener {
        public void onChange(SwitchButton sb, boolean state);
    }

    public void setSwitchState(boolean state) {
        this.mSwitchOn = state;
    }

    @Override
    public void onClick(View v) {
        mDeltX = mSwitchOn ? mMoveLength : -mMoveLength;
        mSwitchOn = !mSwitchOn;
        if (mListener != null) {
            mListener.onChange(this, mSwitchOn);
        }
        invalidate();
        mDeltX = 0;
    }
}
